Telephone system



Oct. 14, 1930. J. WICKS TELEPHONE S YSTEM Filed Aug. 6', 1928 6Sheets-Sheet 1 Oct. 14, 1930. J. WICKS TELEPHONE SYSTEM 6 Sheets-Sheet 2Filed Aug. 6, 1928 Ma g 3 Jo hm Wicks Oct. 14, 1930. J. wlcKs TELEPHONESYSTEM Filed Aug. 6, 1928 s Sheet-Sheet s b NMMQ Inuen or v John MickiOct. 14, 1930. .1. WlCKS TELEPHONE SYSTEM Filed Aug. 6, 1.928 6Sheets-Sheet 4 Nvm Oct. 14, 1930. J. WICKS TELEPHONE SYSTEM Filed Aug.6, 1928 6 Sheets-Sheet 5 Elm Im.ren 1:1 Ja Zm wicks I m wwm PRF P Oct.14, 1930. J. WICKS TELEPHONE SYSTEM Filed Aug. 6, 1928 6 Sheets-Sheet 6wmxi fi -33 John Nicks Patented @ct. 14, 1932 U ITED STATES PATENTOFFIOE.

JOHN WIGKS, OF OAK PARK, ILLINOIS, ASSIGNOR TO RESERVE HOLDING COMPANY,OF KANSAS CITY, MISSOURI, A CORPORATION OF DELAWARE TELEPHONE SYSTEMApplication filed August 6, 1928. Serial No. 297,611.

The present invention relates to telephone systems in general, but asregards a number of its objects and features, it is concerned moreparticularly with automatic telephone systems of the so-called invertedtype in which talking battery and holding potentials are supplied from afirst selector rather than a connector. This case may be considered aswith the present inverted system and to enable a toll operator to cutinon local connections in case either one of the local subscribers isdesired in a toll connection and break down such local connection inorder to complete the desired toll connection. In case the desired localsubscriber is engaged in a toll connection, the toll operator will beautomatically notified of this fact by means of a toll busy tone and shewill be unable to out in and break down such a toll connection.

Another object of the invention is to provide improved metering and zonemetering circuit arrangements for metering the call after thetermination of conversation. Metering on calls is to take place afterthe termination of conversation instead of when the called party answersbecause the completed connection is liable at any time to be interruptedby a toll operator coming in on the connection to establish a desiredtoll connection. Another object of the invention is to pro vide new andimproved selectors and selector repeater circuits such that theselectors hunt .for a battery potential on their associated According toanother feature, a new and improved rotary connector accessible for usein both local and toll connections has been provided to take care of thesituation in which a calling subscriber may call a common call numberand connect with the first idle one of several lines having such acommon call number. Circuit arran ements are also provided in thisimprove connector whereby a calling subscriber can call and conncct witha particular one of these subscribers having a common call number.

There are, of course, a number of objects and features subsidiary to theforegoing which may be understood best from a further perusal of thisspecification.

Referring now to the accompanying drawings comprising Figs. 1 to 7,inclusive, Figs. 1 to 6 show by means of the usual circuit diagrams asufficient amount of equipment.employed in a telephone system embodyingthe principles of the invention to enable the invention to beunderstood. Fig. 7 is a diagram showing how the sheets of drawings, onwhich Figs. 1 to 6 appear, should be arranged in order to be understoodbest.

F ig. 1 shows a two conductor toll service trunk extending from the jackJ at the toll board to the toll transmission selector repeater locatedat the local automatic exchange. Fig. 1 also shows the cord circuit CCwhich is one of the cord circuits used by the toll operator to completeconnections to the toll service trunk through the jacks such as J. Othertrunk lines, such as the trunk line comprising conductors 9 and 10(extend from the toll board to other automatic otlices in this telephonesystem.

Fig. 2 shows the transmission selector repeater on the incoming end ofthe interofiice trunk line comprising conductors 9 and 10 extending fromjack J, Fig. 1. This transmission selector repeater is of a specialdesign so as to give the operator the correct supervision and so as toenable the operator to control the starting of the application ofringing current to the called line. This selector repeater is alsodesigned so as to enable the operator to cut in on a local establishedconnection and break down such connection in order to complete a tollconnection to the desired called subscriber. A transmis- .sion selectorrepeater of the same design is cess to intermediate selectors such astheselectors shown in Fig. 4.

Fig. 3 shows the first selector re eater which is accessibleto the lineswitch L associated with the line of substation A. This selectorrepeater is provided'with the necessary arrangements forfeeding talkingbattery to the calling subscriber in all cases and to the calledsubscriber on local calls. It is also provided withthe necessary arranements for preventingv the operation of t e subscribers meter when theoperator breaks down a local established connection. Circuitarrangements are also provided in the first selector repeater forholding the line switch operated after the callin subscriber hasreplaced his receiver in order to meter the call upon release. Thecircuits are also arranged so that the calling subscriber, in making anew call, will not interfere with the metering operation until themetering operation has been completed.

Fig. 4 shows two intermediate selectors, the first of which is shown indetail and is accessible to the first selector repeater shown in Fig. 3.The second intermediate selector which is similar in all respects to thefirst intermediate selector is accessible from the first intermediateselector and the transmission selector repeater, Fig. 2, located inthelocal automatic exchange.

Figure 5 shows a rotary connector which is accessible to the secondintermediate selector shown in Fig. 4 and is used for calling individuallines and also for calling lines associated in groups with the number ofthe first line assigned as the call number of the entire group. Thisrotary connector is also provided with circuit arrangements such that asubscriber may call a particular line out of a group of lines having thesame directory call number. This connector is provided with circuitarrangements so as to provide a guarding potential of one character incase a local connection has been established or if the connector hasbeen used to complete a toll connection to provide a discriminatingguarding potential on the test contact of the called line. Thisconnector is also provided with means for cutting in on a localconnection and breaking down such local connection.

- The rotary connector has access to subscribers lines such as A and A.The line switch LS is similar to the line switch LS in Fig. 3 and isindividual to the line of subscriber A. i

Fig. 5A shows in detail the mannerin.

which the test contacts accessible to. test wiper 464 of the rotaryconnector are ar-' ranged in order to permit the rotary connector toseize an idle line in a grou of lines in case .the group number is calleand to connect wit group, such as illustrated b contacts 482, in casethe corresponding num er of such intermediate line is called. Asillustrated in Fig. 5A, 480 is the test contact accessible to'wiper 464of the first line of a group of lines, while test contacts 482 areintermediate lines and test contact 483 is the test contact of the lastline in that particular group. Contact 485 is another first test contactin another group .while contact 486 is the last test contact of suchother group. Each first contact-in the group has batter potentialpermanently oonnected thereto y we of the resistances such as 481 and481 wh1le the last test contacts in the-group have ground permanentlyconnected thereto. The test contacts of individual lines, such as 484,and intermediate lines of a grou such as 482, are left dead.

To the left-oi t is shown the trunk meter relays associated with thetrunk comprising conductors 601 and 602 extendin The trunk meter relaysare individual to the trunk and are taken into use when the firstselector repeater is operated to seize the trunk line extending to thedistant automatic exchange. The function of the trunk meter relays areto maintain the first selector'repeater, Fig. 3, in operated position,until the proper number of meterin impulses have can sent 'for operatingt e calling subscribers meter. To the right of the dotted line in Fig. 6there is shown an incoming selector repeater located in the distantautomatic exchange. The incoming selector repeater is accessible tofirst selector repeaters m the local automatic exchange by way of thetrunk line comprising conductors 601 and 602. The incoming selectorrepeater is provided with means for repeating impulses to succeedingswitches in the distant automatic exchange and for providing a holdingcircuit for the same; for operating an answering brid e in the firstselector repeater when the call is answered; for breaking down a localconnection in case an operator desires to complete a toll connection tothe called subscriber; for preventing the operation of the callingsubscribers meter when the connection has been broken down; and forsupplying talking battery to the called subscriber. The incomingselector repeater has access to intermediate selectors such as is shownin Fig. 4 and such intermediate selectors have access to connectorswitches such as shown in Fig. 5, all of which are located in thedistant automatic exchange. The connectors have access to thesubscribers lines terminating in the distant automatic exchange. 1

Regarding the mechanical construction he dotted line in Fig. 6 therefrom the local automatic. exchange to the lstant automatic exchange.

any intermediate line of a of the apparatus shown, the variousselectors, selector repeaters and connectors are mechanically of thewell known vertical and rotary type of switch in which the bank con-'tacts are arranged in horizontal rows or levels.

The various selector repeaters and intermediate selectors are of the tyecommonly referred to as the battery hunting ty l The various lineswitches, such as L and LS, are mechanically of the well known rotarytype of switch in which the wipers are advanced in one direction onlyand are advanced upon the back stroke of their associated steppingmagnets.

The invention having been described generally, a detailed description ofthe operation of the apparatus shown will now be given. For thispurpose, it will be assumed that the subscriber at substation A,desiring to converse with the subscriber at substation A, removes hisreceiver and dials the digits in the telephone number of the subscriberat the substation A.

Calls from substation A to substation A When the receiver is removed atsubstation A, a circuit is closed over line conductors 201 and 202 forline relay 204 of the line switch LS. Line relay 204 energizes over thecalling line and places ground on the associated private normalconductor 218 leading to the banks of the connector switches havingaccess to the line of substation A thereby making this line busy tothose connectors, and also closes a circuit through the combinedswitching and cut-ofi' relay 203 and the motor magnet 205. Line relay204 also at armature 220 connects test wiper 211 through armature 207and its resting contact to the junction of relay 203 and magnet 205.Accordingly, if the trunk upon which the wipers of the switch arestanding is busy the ground potential encountered by test wiper 211shunts the relay 203 and prevents it from energizing and affords adirect circuit for the self-interrupting stepping magnet 205.Accordingly, stepping magnet 205 operates in a buzzer-like manner toadvance the wipers 210 to 213, inclusive, in search of an idle trunkline.

When an idle trunk line is reached, stepping magnet 205 ceases tooperate, and relay 203, being no longer short circuited, energizes inseries with stepping magnet 205, which however, does not operate at thistime on account of the relatively high resistance of relay 203. Uponenergizing, relay 203 disconnects test wiper 211 from thejunction of itsown winding and that of magnet 205 and connects it to the groundedprivate normal conductor 218, thereby extending ground through therelease trunk conductor 215 of the seized trunk; connects up the meteroperating wiper 212 at armature 208; and at armatures 206 and 209disconnects conductors 201 and 202 from line relay 204 and ground andextends them by way of wipers 210 and 213, conductors 214 and 217,armatures 273 and 279 and their resting contacts, and through the upperand lower windings of line relay 221 and relay 224 to battery andground. Line relay 221 energizes over the above traced circuit but relay224 being differential and stifliy adjusted will operate only whenground is connected to both its windings. Line relay 221, uponenergizing, at armature 240 closes a circuit for energizing relays 223and 227 in series; and at armature 241 removes the short circuit fromaround release relay 222 and closes an energizing circuit for releaserelay 222 in series with the vertical magnet 230 and the upper and lowerwindings of relay 226. Release relay 222 energizes over the above tracedcircuit but relay 226 and vertical magnet 230 do not operate because ofthe high resistance of release relay 222. Release relay 222, uponenergizing, at armature 242 closes a shunt around the armature 261; atarmature 244prepares a point in the holding circuit of relay223; atarmature 244 opens a point in the circuit to the release magnet 232; atarmature 245 grounds the release trunk 215 thereby maintaining the lineswitch LS in operated position when ground is removed from armature 219by the deenergization of line relay 204; at armature 246 groundsconductor 233; and at armature 247 completes a locking circuit foritself as well as preparing the impulsing circuit through the verticalmagnet. 223 and 227 may be traced as follows: from The circuit forenergizing relays ground by way of the upper winding of relay 227,normally closed springs controlled by its working contact, upper windingof relay 223 and upper winding of relay 224 to battery. Due to itsspring adjustments relay 224 is not energized over this circuit. Relay223, upon energizing, at armature 249 opens a point in the circuit ofthe release magnet as well as opening a. point in the circuit foroperating the calling subscribers meter and at armature 250 prepares anenergizing circuit for relay 225 which, however, is opened at armature270 at this time. Relay 227, upon energizing, at armature 266 connectsup ground through resistance 267 in order to maintain relay 223energized during impulsing; at armature 268 and its working contactconnects the dial tone to conductor 214; at armature 269 removes theshunt circuit from around the upper winding of relay 228; at armature270 and its resting contact opens a point in the circuit of relay 225and at its working contact completes a locking circuit for itself,extending from ground by way of armature 250; and at armature 271prepares a circuit for grounding wiper 292 while the first selectorrepeater is repeating impulses desired level of bank contacts.

to the succeeding switches in order to improve the impulsing circuit.

Dial toneextends by way of conductor 272, normally closed off-normalsprings 265, working contact'of armature 268 and said armature,condenser 274, resting contact of armature 273 and said armature;conductor 214,

wiper 210, working contact of armature 206 and said armature, conductor201, over the calling loop, through conductor 202, armature 209 and itsworking contact, wiper 213,

. conductor 217, armature 279 and its resting ture 241, armature 283 andits resting contact, and through the winding of vertical magnet 230 tobattery. By the operation of i the vertical magnet 230 the switch wipers290 to 292, inclusive, are operated opposite the A branch of thisimpulsing circuit extends through the lower and upper windings of relay226 to battery, causing such relay to energize. Relay 221 at armature241, in addition to closing the impulsing circuit, also closes a shortcircuit around release relay 222 in order to render the release relaslow to release so that it will be maintaine in operated position duringthe impulsing period. At armature 240 line relay 221 closes a circuitextending by way of ground through resistance 267, working contact ofarmature 266, armature 257 armature 243, make-before-break springscontrolled by armature 240, upper winding of relay 223, and upperwinding of relay 224 to battery for maintaining relay 223 energized theimpulsing period.

Relay 226, upon energizing, at armature 261 opens the initial energizingcircuit for line relay 221; at armature 262 opens up a point in thecircuit for the rotary magnet 231 so that the rotary magnet will notoperate when the ofl-normal springs 252 operate and close on the firstvertical step of the switch; at armature 263 opens a point in thecircuit for relay 225; and at armature 264 connects up ground in orderto improve the imnulsing circuit to the succeeding switches. Relay 226is slightly slow to fall back when its circuit is open during theimpulsing period because of the current flow through relay 222. However,after impulsing, relay 226 falls back after a certain period of time. Atarmature 262 relay 226 closes a circuit for operating the rotary magnet231 as follows from ground on release trunk conductor 215, armature 255,armature 278, armature 262 and itsresting contact, armature 251,off-normal spri: gs 252, resting contact of armature 281 and saidarmature, interrupter springs-288 of rotary magnet, and winding ofrotary magnet 231 to battery. By the operation of the rotary magnet 231,the switch wipers 290 to 292, inclusive, are rotated into engagementwith the first set of bank contacts in the selected level. Near the endof its stroke, rotary magnet 231 operates its interrupter springs 288,thereby interrupting its own circuit and the operation of the rotarymagnet continues in a buzzerlike manner to ste the wipers over the'bankcontacts in the se ected level until the test wiper 291 encounters abattery potential on one of the test contacts.

Assuming that the first idle trunk comprises the conductors 301 to 303,inclusive, extending to the intermediate selector shown in Fig. 4, thenwhen wiper 291 encounters test contact 298 a circuit may. be traced forenergizing switching relay 229 as follows: ground by way of groundedconductor 233, armature 269 and its working contact, up er winding ofswitching relay 229, Wiper 91, test contact 298, conductor 302, armature310, normally closed springs controlled by armature 316, normally closedoff-normal springs 312, and through resistance 345 to battery. From theforegoing, it will be seen that the rotary magnet rotates the switchWipers until the test wiper 291 engages a test contact having battepotential thereon and therefore the first se ector repeater willnot stopon grounded test contacts or contacts upon which there are no potentialswhatever. Relay 229, upon energizin at armatures 280 and 284 closes acircuit or energizing line relay 304 of the intermediate selector; at

armature 281 opens the rotary magnet circuit so as to stop the rotationof the switch and closes a locking circuit for itself extending by wayof grounded release trunk conductor 215 through its lower winding andwinding of-the rotary magnet in series to battery; at

armature 282 prepares a circuit for short cir-' cuiting the upperwinding of switching relay 229 and connects groundpotential extending byway of grounded conductor 233 through the upper low resistance windingof relay 228 to conductor 302; and at armature 283 opens termediateselector may be tracedas follows: ground by way of lower winding ofrelay 224, lower winding of relay 223, normally closed springscontrolled by armature 279, armature 284, wiper 292, contact 299,conductor 303, normally closed springs controlled by armature 323,winding of line relay 304, normally closed springs controlled byarmature 319, conductor 301, bank contact 297, wiper 290, armature 280and its working contact, normally closed strings controlled by armature273, armature 240 and its working contact, upper. winding of relay 223,and upper winding of relay 224 to battery. Line relay 304 energizes overthe above-traced circuit and relay 223 is maintained in operatedposition when its initial energizing circuit is opened at armature 280.

Line relay 304, upon energizing, at armature 310 opens the short circuitaround the winding of relay 305, thereby permitting relay 305 toenergize, and at armature 311 prepares the impulsing circuit for thevertical magnet. The circuit for energizing relay 305 may be traced asfollows: from grounded conductor 302, by way of normally closed eleventhrotary step contacts 317, armature 320 and its resting contact, windingof relay 305, normally closed off-normal spring 312 and throughresistance 345 to battery. Relay 305 immediately-energizes and atarmature 314 opens the circuit to the rotary magnet; at armature 315prepares the impulsing circuit to the vertical magnet and opens a pointin the circuit to the release magnet 309; and at armature 316 prepares anew holding circuit for itself by shunting the normally closedoff-normal springs 312 which will open on the first vertical step of theswitch.

The calling subscriber may now dial the second digit in the callednumber and responsive thereto line relay 221 in the first selectorrepeater operates in the same man ner as previously described. Each timeline relay 221 deenergizes. said relay at armature 240 opens theimpulsing circuit extending to the line relay 304 in the intermediateselector. In addition, at armature 241 line relav 221 again completesthe circuit for relay 226 so that the latter relay will energize andconnect ground by way of armature 264 to conductor 303 so as to improvethe impulsing circuit.

In the intermediate selector, line relay 304 responds to theinterruptions in its circuit and at each deenergization operates thever- 311, armature 315 and its working'contact,-

and winding of vertical magnet 307 to battery. On the first verticaloperation of the switch the normally open elf-normal springs 312 closeandprepare a circuit for shunting relay 305. During impulsing, however,relay 305 is intermittently energized and shunted by line relay 304 andtherefore relay 305 is maintained in ener ized position during theimpulsing period. Shortly after the transmission of impulses, relay 305is shunted for a suificient time or time enough to permit such relay tobe deenergized. The short circuit of relay 305 may be traced as follows:grounded conductor 302, normally closed springs 317, armature 320 andits resting contact, winding of rela 305 working contact of armature 316an said armature, normally open springs 312 (now closed), armature 311and its working contact, and resting contact of armature 322 and saidarmature to ground. Relay 305, upon deenergizing, at armature 314 closesa cirsuit for operating the rotary magnet 308;

cuit; and at armature 316 opens a point in the shunt circuit arounditself. The circuit for energizing the rotary magnet 308 may be tracedas follows: ground by way of armature 322, working contact of armature311-and said armature, armature 314, interrupter springs 313 of therotary magnet and through the winding of rotary magnet 308 to battery.Rotary magnet 308 energizes and interrupts its own circuit in a buzzerlike manner to rotate the wipers in search of an idle trunk. Rotarymagnet 308 continues to rotate the wipers over the bank contacts untilan idle trunk is encountered, that is, until the wiper 327 encounters acontact having battery potential thereon.

Assuming that the second intermediate selector shown just to the right,is the first idle intermediate selector in this level, then there willbe a battery potential on test contact 330 extending to a resistance,similar to resistance 345 in the first intermediate selector. When wiper327 encounters the battery potential on test contact 330. switch ingrelay 306 energizes over the following circuit: ground by way ofgrounded release trunk conductor 302, lower winding) of switching relay306, test wiper 327, ank contact 330, release trunk conductor 333, andover a similar circuit to a resistance, similar to 345, and battery.Relay 306, upon energizing, at armature 320 disconnects relay 305 andconnects the release trunk 302 straight through to release trunk 333 andalso short circuits the lower energizing winding of switching relay 306;at armature 321 completes a locking circuit for itself through its upperwinding to grounded release trunk conductor 302; p at armature 322 opensa point in the circuit for the release magnet 309; and at armatures 319and 323 disconnects the line relay 304 and connects the talkingconductors 301 and 303 to the talk- .ing conductors 332 and 334,respectively.

The deenergiza-tion of line relay 304 is without effect at this timeother than to close a pognt in the circuit for the release magnet 30 Thesecond intermediate selector seized over conductors 332 to 334, beingsimilar in all respects to the intermediate selector just 1 described,will therefore operate in the same manner and seize an idle trunk,suclias the trunk comprising conductors 341 to 343, ex-

.tending to an idle connector responsive to the next series of impulses.

Assuming that the connector in Fig. 5is

the connector seized, the circuit for energizing the switching relay ofthe second intermediate selector may be traced as follows: ground by wayof grounded release trunk conductor 333, winding of switchingrelay, testwiper 336, bank contact 339, conductor 342 armature 417 and its restingcontact, normally closed ofi-normal springs 443. and

through the upper winding of relay 405 to battery and alsoby way ofnormally closed springs controlled byarmature 436, and resistance 442 tobattery. Relay 405 in the connector does not operate until the switchingrelay in the second intermediate selector short circuits its upperwinding, thereby permitting sufiicient current flow to energize relay405.

When the second intermediate selector cuts through a circuit iscompleted for energizing line relay 402 of the connector as follows:from ground and battery through the upper and lower windings of relays223 and 224 of the first selector repeater by way of the circuitpreviously traced over conductors 301 and 303, over conductors 332 and334, con-' ductors 341 and 343, armatures 447 and 452 and their restingcontacts, and through the at armatures 434 and 438 disconnectsinterrupted. generator and generator ground; at armature 435 preparesthe impulsing circuit; at armature 436 disconnects the resistance 442and completes a locking circuit for itself extending by way of groundedrelease trunk conductor 342; and at armature 437 opens a point in thecircuit of the release magnet 412.

The calling subscriber may now dial the next digit of the called numberand accordingly the line relay of the first selector interrupts the loopcircuit extending to the line relay 402 of the connector. Each time thecircuit of line relay 402 is opened said relay deenergizes and atarmature 419 closes a circuit for operating the vertical magnet 410 asfollows: ground by way of armature 435, normally closed springscontrolled by armature 419, armature 448 and its resting contactarmature 430, armature 416 and its resting contact and winding ofvertical magnet 410 to battery. By the operation of the vertical magnetthe switch wipers 463 to 466 are operated in the well known manneropposite the desired'level of bank contacts in' which the called. lineterminates. During impulsing, a circuit mayv be traced for slow actingrelay 406 as follows from ground by way of armature 435 by way of thepreviously traced impulsing circuit to armature 430,

and thence byway of armature 458 and its resting contact to the windingof relay 406 and battery. Slow acting relay 406, upon energizing, atarmature 440 shunts'the contacts 430 of the busy relay 404; at armature441 prepares a point in the circuit for the busy relay 404; at armature444 shunts the busy relay contacts 432; and at armature 445 opens apoint in the circuit of relays 401 and 409. Upon the first vertical stepof the connector, off-normal springs 420 close and complete a circuitfor energizing slow acting relay 408 when line relay 402'is in energizedposition as follows: ground by way of armature 435, working contact ofarmature 419 and said armature, off-normal springs 420, and winding ofslow acting relay'408 to battery. Relay 408, upon energizing, atarmature 455 prepares a point in the circuit for relay 407 at armature456 prepares a cir cuit for grounding the lower talking conductor 343;and at'armature 457 prepares a circuit for energizing relay 401. At theoffnormal springs414 a circuit for the release magnet is prepared and atoff-normal springs 443 the original energizing circuit of relay 405 isopened. I

After receipt of thisoseries of impulses slow acting relay 406deenergizes and at armature 445 completes a circuit for energizing relay401 as follows: ground by way of armature 457, armature 445, armature433 and its resting contact, and winding of relay 401 to battery. Relay401, upon energizing, at armature 415 prepares a locking circuit forswitching relay 407 at armature 416 opens the vertical magnet circuitand prepares the rotary magnet circuit; at armature 417 opens thelocking circuit of relay 405 and closes a looking circuit for itself;and at armature 418 opens a point in the circuit of the release magnet412 and connects ground by way of off-normal springs 414 to replace theground which will shortly be removed at armature 435. The deenergizationof relay 405 is without effect at this time other than to prepare theringing circuit.

It will now be assumed that the calling subscriber Wishes to talk to anyone of a group of subscribers, each having the same group call number.Assuming further that the desired group is the first groupdiagrammatically illustrated in Fig. A, the calling subscriber will thendial the group number, or in this case the digit 1. Responsive to thecalling subscriberls dialling the digit 1, the line relay 402 isoperated in the same manner as previously described, and upon itsdeenergization, responsive to the impulse, it will close at armature 419the circuit for operating the rotary magnet. The circuit for operatingthe rotary magnet may be traced as follows:

ground by way of off-normal springs 414,

armature 418 and its working contact, normally closed springs controlledby armature 419, armature 448 and its resting contact, armature 430,armature 416 and its working contact, and winding of rotary magnet 411to battery. The rotary magnet 411 operates the wipers in engagement withthe first set of bank contacts, and wiper 464 will therefore be inengagement with test contact 480 (Fig. 5A) which has a battery potentialthereon.

The operation of the rotary connector now depends u on whether the firstline associated with the rst set of contacts is busy or idle. If busy,there will be a ground potential on the test contact engaged by testwiper 465 and accordingly busy relay 404 energizes over the followingcircuit: ground by way of grounded test contact, wiper465, armature 441and its workin contact, and winding of busy relay 404 to attery. Busyrelay 404, upon energizing, at armature 429 prepares the circuit forconnecting the busy tone to the calling line; at armature 431 prepares alocking circuit for itself which is completed when slow acting relay 406falls back; at armature 433 prepares a circuit for relay 409; and atarmature 432 opens the circuit to the upper winding of line relay 402which deenergizes when re ay 406 falls back. When slow acting relay 406falls back a short interval of time after the directive rotary impulses,a circuit may be traced for energizing relay 409 as follows: from groundby way of armature 457, armature 445, armature 433 and its workingcontact, lower winding of relay 409, normally closed springs controlledby armature 461,

.. test wiper 464, test contact 480, and through resistance 481 tobattery. Relay 409, upon energizing, at armature 458 opens the circuitof slow acting relay 406; at armature 459 com- Eletes a locking circuitfor itself extending y way of grounded test contacts accessible to testwiper 465; at armature 461 opens its original energizing circuit andcloses an en ergizing circuit through the lower winding of relay 402;and at armature 462 grounds such armature for a purpose which will bedescribed hereinafter. The circuit for ener gizing line relay 402 may betraced as follows: ground by way of interrupter contact 413 of therotary magnet, lower winding of linerelay 402, normally open springscontrolled by armature 461, and resistance 460 to battery. Line relay402, upon energizing, at armature 419 again completes the circuit formaintaining slow acting relay 408 in energized positlon and also closesa circuit for operating the rotary magnet 411 as follows: ground by wayof ofi-normal springs 414, armature 418 and its working contact, workingcontact of armature 419 and said armature, off-normal springs 420,working contact of armature 458 and said armature, armature 416 and itsworking contact, and winding of rotary magnet 411 to battery. The rotarymagnet operates and steps the wipers to the next set of contacts in thedesired group. Near the end of its stroke, rotary magnet 411 at armature413 opens the circuit of line relay 402, whereupon said relaydeenergizes. Line relay 402, upon deenergizing, at armature 419 opensthe circuit of the rotary magnet and slow acting relay 408. If the nexttrunk line is busy, relay 409 will be maintained energized by way of thegrounded contacts in engagement with Wiper 465 and therefore, when therotary magnet restores armature 413, the line relay is again energizedand again causes the rotary magnet to step the wipers to the next set ofbank contacts. This cycle of operation continues until an idle line orthe last line in the group is reached.

Assuming that all the lines in the desired group are busy, the connectorwill rotate its wipers into engagement with the last line in the groupwhere a ground potential will be encountered by wi er 464 which willprevent line relay 402 rom again energizing. The ground on the last testcontact such as 483 extends by way of wiper 464, working contact ofarmature 461 and said armature, through relay 402 to ground at armature413, thereby shunting relay 402. Relay 409, however, is maintained inenergized position from ground encountered by the test wiper 465. Sincethe line relay 402 is not again energized to close the circuit to therotary magnet, the wipers accordingly come to rest on the bank contactsof the last line in the group. The busy tone is now transmitted to thecalling subscriber by way of conductor 421, resting contact of armature422 and said armature, armature 429, resting contact of armature 447 andsaid armature, to the upper talking conductor 341 from whence it istransmitted to the' calling subscriber in the well known manner.

Returning to the first selector repeater, the loop circuit of relay 223will be interrupted when the circuit through the upper winding of linerelay 402 of the connector is opened by the energization and locking upof the busy relay 404. Relay 223 accordingly deenergizes. At armature250relay 223 opens not close the meter circuit at armature 256.

Responsive to the busy tone, the calling sub-- scriber will replace h1sreceiver and release the switches in the same manner as will bedescribed hereinafter.

Assuming now that one of the group of subscribers lines, for instancesubscriber A, is idle, the connector will rotate its wi ers intoengagement with bank contacts 46 to 470, inclusive, and since the lineof substa tion A is idle there will be a battery potential on testcontact 469 instead of ground and therefore relay 409 will bedeenergized. Relay 409, upon deenergizing, at armature 459 opens its ownlocking circuit and also closes an energizing circuit for switch-throughrelay 407 as follows: from ground by way of the lower windin ofswitching relay. 407, resting contact 0% armature 459 and said armature,working contact of armature. 455 and said armature, resting contact ofarmature 441 and said armature, wiper 465, bank contact469, winding ofswitching relay 471 of line switch LS, and through the windin 7 ofrotary magnet 473 to battery. Relays 40 and 471 energize over theabove-traced circuit but the stepping magnet 4730f the line switch LSdoes not receive sufficient current to permit it to operativelyenergize. The combined switching and cut-off relay 471 of the lineswitch LS disconnects the called subscribers line from battery andground in the well known manner. Relay 407, upon energizing, at armature447 opens a point in the circuit of the upper winding of line relay 402causing relays 223 and 227 in the first selector repeater to bedenergized in the manner previously described; at armature 448 opens thecircuit to the rotary magnet; at armature 449 connects direct ground totest contact 469 and multiples thereof to render the called line busyand to hold the called line switch in operated. position; at arm- -m 450opens the locking circuit of the busy relay 404 which now deenergizes;at armature 451 closes a locking circuit for itself in series with thevertical magnet 410; at armature 452 completes the ring-backcircuitthrough condenser 454; and at armatures 446 and 453 completes theringing circuit from interrupted generator. Due to the high resistanceof the upper winding of switching relay 407 the vertical magnet does notreceive sufiicient current to operate. The ringing circuit for ringinthe called subscriber may be traced as ollows: from inenergizes when theswitching rela terrupted generator INT GEN, conductor 439, lower windingof ring-cut-ofi relay 405, resting contact of armature 438 and saidarmature, armature 453, wiper 466, contact 470, over the calledsubscribers. line including the ringer of the called line, contact 467,wiper 463, armature ,446,and armature 434 and its resting contact toground.

When the called subscriber answers, ringc'ut-oif relay 405 is energizedover its lower winding. Ring-cut-olf relay, upon energizing. atarmatures 434 and 438 disconnects the ringing current and completes thetalking circuit; at armature 436 again completes a lockingcircui-t foritself which extends by way of the working contact of armature 448 i Iand said armature to ground at either armatures 435 or oif-normalsprings 414; and at armature 437 opens a point in the circuit to vtherelease magnet 412.

Returning now to the first selector repeater, it will be-remembered thatrelay 2% de- 407 of the connector switches through an that relay 223opens the locking circuit of relay 227,

thereby permitting relay 227 to release. As

soon as the calledman' answers, ring-cut-off relay 405 of the connectorcompletes a circuit for energizing relay 223 of the first selectorrepeater over the called subscribers loop. Relay 223, upon energizing,at armature 250 completes anenergizing circuit for slow acting relay.225 as follows: ground by way of armature 250 and its working contact,arma ture 270 and its resting contact, resting contact of armature 263and said armature, and

winding of slow acting relay 225'to battery.

Slow acting relay 225, upon energizing, at

armature 256' opens a point in the circuit to 1 the release magnet 232and also prepares a point in the circuit for operating the callingsubscribers meter; at armature 257 opens a point in the holding circuitfor relay 223; at armature 258 completes a locking circuit for itself;at armature 259 prepares a locking circuit for relay 226; and atarmature 260 prepares a circuit for grounding the lower talkingconductor for supervisory purposes. Talking battery to the callingsubscriber extends by way of the windings of relays 224and 221 over thecalling subscribers loop and talking battery to the called subscriberextends through the windings of relays 224 and 223 over the calledsubscribers loop. The-talking circuit to the various switches may betraced by the heavy talking conductors.

After conversation and responsive to the called subscriber replacing hisreceiver, relay 223 in the first selector repeater deenergizes andprepares the metering and release circuits at armature 249 and atarmature 250 opens one of the locking circuits of slow acting relay 225.

' slow to release.

When the calling subscriber'replaces his receiver linerelay 221releases. Line relay 221, upon deenergizing, at armature 240 opens apoint in the circuit ofrelay 223 and at armature 241 closes a shortcircuit around release relay 222, thereby renderingsuch relay Before therelease relay 222 deenergizes, a circuit may be .traced from ground byWay of armature 247, normally closed springs controlled by armature 241,armature 283 and its working contact, and through the upper winding ofrelay 226 to battery. Relay 226, upon energizing, at armature 261 opensa point in the circiiit of line relay 221 and at armature 262 connectsan additional ground to release trunk conductor- 215 by way of armatures278 and 255 to maintain the calling line switch in operated positionduring the metering operation. After an interval, release relay 222releases and at armature 242 opens another point in the circuit of linerelay 221 sothat the calling subscriber can not interfere with themetering operation. At armature 244 relay 222 closes a circuit foroperating the calling subscribers meter as follows: ground by way ofmeter magnet M, armature 208, wiper 212, conductor 216, armature 256,armature 275, armature 244, armature 249, olf-normal springs 248, and tothe winding of release magnet 232 to battery. Release magnet 232 is notenergized over this circuit on account of the high resistance of themeter magnet M. At armature 245 release relay 222 removes one of theground connections from release trunk conductor 215; at armature 246removes'one of the locking grounds from the locking circuits of relays225 and 226 as well as removing ground from release trunk conductor 302;and at armature 247 release relay 222 opens the locking circuits ofrelays 225 and 226. After an interval of time, relays 225 and 22.6 willrelease, it being remembered that relay 226 is slightly slow to releasedue to the short circuit from its lower winding. Relay 226, upondeenergizing, at armatures 262 removes ground from the release trunkconductor 215, thereby permit ting the calling line switch LS to releasein the well known manner. Relay 225, upon releasing, at armature 256opens the metering circuit and closes a circuit for operating therelease magnets as follows: ground by way of armature 256, armature 275,armature 244,

armature 249, off-normal springs 248, and

through the winding of release magnet 232 to battery. Relay 226 atarmature 262 also opens the locking circuit of switching relay 229whereupon such relay deenergizes and disconnects the talking conductor.By the operation of the release magnet 232 the first selector repeateris returned to its normal position in the well known manner, therebyopening the off-normal springs 248 which in turn opens the circuit ofthe release magnet.

In case the calling man hangs up before the called man, line relay 221will release and open the circuit of relay 223 at armature 240 so thatthe release of the first selector repeater is the same as if the calledman had replaced his receiver.

When ground is removed from release vtrunk conductor 302 by thedeenergization of releaserelay 222, relays 306 in the intermediateselectors and relay 401 of the connector deenergize. Relays 306 in theintermediate selectors, upon deenergizing, at armatures 322 close thecircuitfor their respective release magnets, thereby causing the releaseof the intermediate selectors in the well known manner.

When the combined'change-over and release relay 401 in the connectorreleases, said relay at armature 415 opens the circuit of relay 407 incase the called subscriber has replaced his receiver. In case however,the called subscriber has not hung up his receiver a circuit formaintaining switching relay 407 energized may be traced as follows: fromground by way of upper winding of switching relay 407, armature 451,normally closed springs controlled by armature 415,

working contact of armature 438 and said armature, armature 453, overthe called subscribers loop to armature 446, armature 434, armature 447and its working contact, armature 415 and its resting contact, andwinding of vertical magnet 410 to battery. Relay 407 maintainsring-cut-ofiv relay 405 in operated positionand therefore the connectordoes not release until the called man hangs .net 412. Switching relay407, upon deenergizing, responsive to the deenergization of relay 401 orthe calling subscriber replacing his receiver at armatures 446 and 453opens the talking circuit; at armature 448 opens the holding circuit ofring cutofi relay 405 and removes ground from release trunk 342 whichhas been placed thereon by the deenergization of relay 401 in order tomake the connector test busy as long as it is held by the calledsubscriber; at armature 449' removes ground from test contact 469thereby rendering the called line idle and permitting the release ofrelay 471 to normal; and at armature 451 opens its own locking circuit.Ring cut-ofl relay 405, upon deenergizing, at armature 437 closes thecircuit to the release magnet 412 whereupon said magnet releases theswitch in the well known manner. All of the apparatus involved in thelocal connec- III Ill

tor is therefore recallin tion' is now released and may be used ex tendother calls.

Toll call to subscriber A I Havin described the detailed operation whichta es place in the establishment of a connection, subscriber A tosubscriber A, we will now describe the operation which takes place whensubscriber A is desired ina toll connection. It will now be assumed thatthe toll operator at the switchboard'shown in Fig. 1 desires to extend aconnection to the line of substation A,-either because he has received along distance call for him, or because he himself has requested that along distance connection be set u and the operahim. The operations arethe same in hot csases. To extend the connection to the line ofsubstation A, the operator inserts the plu of her cord circuit, forexample, the (plug of the cord circuit CC, into the jack of a tollservice trunk line terminating at her switchboard and extending to thetransmission selector repeater in the local'automatic exchange. 7

Responsive to the insertion of a plug P into jack J a circuit may betraced for energizing the, line relay 107 of the transmission selectorrepeater as follows: ground by way of normally closed springs controlledby armature 125, lower left hand winding of repeating coil, trunkconductor 10, ring spring of jack J, ring contact of plug P, normallyclosed springs of the combined dial and ringing key K tip contact ofplug P ,tip springs of jack J, trunk conductor 9, upper eft hand windingof the repeating coil in the transmission selector repeater, normallyclosed springs controlled by armature 123, normally closed springscontrolled by armature 128. and to the lower winding of line relay 107to battery. Polarized relay 2 is not energized over the above tracedcircuit because the direction of current flow is not in the properdirection. Line relay 107, upon energizing, at armature 134 prepares acircuit to the upper winding of relay 113 and also prepares the loopreeating circuit. mature 135 relay 10% opens a point in the circuit of therelease magnet 120 and closes a circuit for energizing relay 108.-Release 108, upon energizing, at armature 137 prepares aholding circuitfor relay-.113 during impulsing; at armature 138 grounds thereleasetrunk conductor 121; at armature 139 opens a further point in thecircuit of the release magnet and prepares the impulsing circuit to thevertical magnet 118; and at armature 141 closes a circuit for energizingrelay 106 by way of armature 126 and its lower winding. Relay 106, uponenergizing, at armature 131 disconnects the ringing circuit and closes acircuit for energizing relays 113 and 116 in series; atarmature 132closes a shunt around armature 126 inorder to maintain 'it- At arthecall to the line of substation A. .the operator has dialled the completenumself in energized position in case relay'102 should energizeprematurely; and at armature 133 disconnects generator ground andprepares a locking circuit for the lower windmg of relay 113. Thecircuit for energizing re ays 113 and 116 may be traced as follows:ground by Way of armature150 and its restmg contact, upper Winding ofrelay 113, working contact of armature 134 and said armature, normallyclosed springs controlled by armature 177, armature 154, up er righthand winding of repeating coil, wor ing contact of armature 131 and saidarmature, resting contact of armature 166 and said armature, armature175, normally closed sprin s controlled by armature 182, and through t1e upper winding of relay 116 to battery, Relay 113, u on energizing, atarmature 163 prepares a locking circuit for relay 116. Relay 116, uponenergizing, at armature 174 prepares the dial tone circuit; at armature175 opens a point in the original energizing circuit of relay 116; atarmature 176 prepares a circuit for maintaining relay 113 energizedduring the impulsing period at armature 177 opens a further point in theinitial energizing circuit of relays 113 and 116 and substitutesaholding circuit for relays 113 and 116 in series; at armature 178 opensthe circuit of relaly 102 which does not have time to operate w en therelease trunk 121 was grounded because of its mechanical constructionand also closes a circuit for energizing relay 114; at armature 179opens the circuit of relay 104 and also closes a locking circuit foritself; at

mature 17 8 and said armature, resistance 173 and winding of relay 114to battery. Relay 114, upon energizing, at armature 165 completes thecircuit for transmitting the dial tone to the operator; at armature 166opens a point in the talking circuit; at armature 16 prepares a circuitfor relay and at armature 169 prepares a circuit for relay 1'15.Responsive to the seizure of the switch, relays 106, 107, 108, 113, 114,and 116 are operated in order to prepare the transmission selectorrepeater for operation. 7

The callmg operator now throws her combined dialling and ringing keyinto dialling position, thereby connecting up her common calling deviceCD in bridge of the tip and ring conductors of the plug P. The opera-.torwill now operate the calling device in accordance with the digitsnecessary to trunk After her she will restore the combined dialling andr nging key to normal position.

Responsive to the operation of the calling The rotary magnet willcontinue to operate in a buzzer like manner until the test wiper devicethe circuit of line relay 107 is intermittently opened and closed andsaid relay intermittently deenergizes and energizes responsive thereto.Each time line relay 107 falls back a circuit may be traced foroperating the vertical magnet and slow acting relay 109. The circuit forenergizing the vertical magnet may be traced as follows: ground by wayof normally closed springs controlled by armature 135, armature 139 andits working contact, armature 182, and through the winding of verticalmagnet 118 to battery. A branch of this circuit also extends through thewinding of slow acting relay 109 and such relay due to its slow. actingcharacteristics is maintained in operated position during the diallingperiod. At armature 134 line relay 107 closes a circuit for maintainingrelay 113 in operated position during impulsing. This circuit extends byway of armature 150, the

7 upper winding of relay 1'13, make before break springs controlled byarmature 134, armature 137, armature 136 and through resistance 183 tobattery. Slow acting relay 109, upon energizing, at armature 143 opens apoint in the circuit of slow acting relay 110 and at armature 144 opensa point in the circuit for the rotary magnet 119. By the operation ofthe rotary magnet the switch wipers 191 to 193, inclusive, are operatedopposite the desired levels of bank contacts inwhich an intermediateselector such as shown in Fig. 4 terminates. I

A short time after the receipt of the first series of impulses slowacting relay 109 deenergizes and at armature 144 closes the circuit forrotary magnet 119 which may be traced as follows: ground by way ofarms;- ture 141, armature 144, armature 140, 011'.- normal s rings 181which were closed on the first vertical step of the switch, restingcontact of armature 185 and said armature, interrupter springs 158 ofthe rotary magnet, and winding of rotary magnet 119 to battery. By theoperation of the rotary magnet, the switch wipers are rotated intoengagement with the first step of bank contacts 1n the desired level.The operation of the transmission selector repeater now depends uponwhether the first trunk line is busy or not.

192 encounters an idle trunk which will have a battery potentialconnected to its associated test contact, such as 195. Assuming that thefirst idle trunk encountered by test wiper 192 comprises the conductors197 to 198 then there will be a battery potential on test contact 195extending from the second intermediate selector through the resistance,such as 345, over conductors 333 and.198 to bank contact 195. As soon astest wiper 192 encounters the test contact 195 having battery potentialthereon, switching relay 117 energizes over its upper winding from thenet; at armature 186 opens the circuit to the vertical magnet 118; andat armatures 182 and 187 closes a point in the talking circuit therebyclosing a circuit for energizing the line relay in the intermediateselector. The line relay of the seized intermediate selector energizesand prepares the switch for operatibnin the same manner as previouslydescribed.

The circuit for energizing the line relay of the seized intermediateselector extends from ground by way of armature 150, upper winding ofrelay 113, working contact of armature 134 and said armature, workingcontact of armature 177 and said armature, working contact of armature182 and said armature, wiper 191, contact-194, conductor 197, conductor332, winding of line relay, such as line relay 304, conductor 334,conductor 199, bank contact 196, wiper 193, armature 187 annature 181and its working contact, and through resistance 172 to battery. Relay113 is maintained energized over the above traced circuit. Y

The operator may ,now dial the next digit of the called number andresponsive thereto line relay 107 in the transmission selector re- 1peater is operated in the same manner as previously described. Each timethe circuit of line relay 107 is opened, said relay deenergizes and atarmature 134 opens the circuit of the line relay in the intermediateselector. Relay 113, however, is maintained from battery throughresistance 183 over the circuit previously traced. Relay 109 is againenergized but does not perform any useful functions at this time.Responsive to the interruption in its circuit, the line relay of theintermediate selector operates in the same manner as previouslydescribed to cause the intermediate selector to seize an idle trunkextending to an idle connector. Assuming that the connector shown inFig. 5 is again seized, then line relay 402 again operates, this timefrom ground at armature 150 and battery through resistance 172 over thetalking conductors extending between the transmission selector repeaterand the connector. It will be noted that the flow of current extendingover the talking conductors from the transmission selector repeater tothe connector is reversed with respect to the flow of current extendingover the talking conductors from the first se- I the same manner aspreviously described when the release trunk conductor is grounded. lheoperator may now dial the next digit in the number of the calledsubscriber. Responsive thereto, line relay 107 in the transmissionselector repeater repeats the impulses to line relay 402' in the rotaryconnector, thereby operating the connector wipers opposite the desiredgroupof bank contacts in which the called line terminates. Relays 406,408, and 401 operate in the same manner as previously described. --Whenrelay 401 energizes after the first series of impulses, said relaycloses a circuit at armature 417 through resistance 426 to the lowerwind- 7 ing of marginal relayv 403. The fiow of current through both thewinding of relay 403 is now suflicient to operate armature 425. Armature425, upon closing its make-contact, short circuits the resistance 426,thereby causing the marginal relay to pull all the way up and lock tothe grounded release trunk conduotor 342. Relay 403, upon energizing, atarmature 422 opens a point in the circuit extending to the busy tonemachine; at armature 423 maintains the ring-cut-ofi relay in energizedposition so that the operator may control the application of ringingcurrent; at armature 424 disconnects direct ground so that groundthrough a resistance 428 will be applied to the test contact of thecalled line when the connector switches through; and at armature 427prepares a circuit for grounding conductor 343.

Assuming now that the operator desires to connect with a particularline, such as substation A', in a group of lines all having the samecommon called number, she will therefore dial the individual call numberof substation A. Assume further that substation A is the desiredsubscriber and that the line of substation A terminates in the fourthset of contacts in the level to which the connector has been operated,the operator will therefore dial the digit 4. Responsive to the operatordialling the digit 4, the line relay in the transmission selectorrepeater repeats the impulses to line relay 402 in the rotary connectorwhereupon line relay 402 operates the ro tary magnet to cause the wipersto come to rest in engagment with the fourth set of bank contacts in theselected level, or the bank contacts individual to the called subscriberA. Since only the first contact in a group has battery potential on testcontacts such as con tacts 480 and 485, (Fig. A) relay 409 will not beenergized because its circuit is opened at armature 445 when wiper 464passes over the first contact in the group.

Assuming now that substationA' is idle, switching relay 407 willenergize in series with switching relay 471 of the called line switch LSin the same manner as previously described. Switching relay 407, uponenergizing, at armature 447 opens the circuit of ine relay 402; atarmature 448 opens the rotary magnet circuit; at armature 449 connectsground through resistance 428 to test contact 469 thereby applying adiscriminating ground potential instead of direct ground; at armature451 locks itself in series with the vertical magnet 410; and atarmatures 446 and 453 connects up the talking conductors. Line relay402,'upon deenergizing, at armature 419 opens the circuit of slow actingrelay 408. After an interval, slow acting relay 408 deenergizes and atarmature 456 prepares a, oint in the circuit for the lower winding 0switching relay 407.

Returning now to the toll transmission selector, the circuit of relay113 is opened when switching relay 407 of the connector opens the loopat armature 447 and accordingly relay 113 deenergizes'. Relay 113, upondeenergizing, at armature 163 opens the ocking circuit of relay 116whereupon the latter relay deenergizes. Relay 116, upon deenergizing, atarmature 174 prepares the busy circuit; at armatures 175 and 181preparesthe talking circuit; at armature 176 opens a point in theholding circuit of relay 113; at armature 177 disconnects relay 113 fromwiper 191; at armature 178 opens the circuit of relay 114 and completesa circuit for relay 102; at armature 179 prepares a point in the circuitfor relay 104; and at armature 180 closes the circuit for energizingrelay 115 which energizes and causes slow acting relay 109 to energizealso. After a short interval of time, relay 114 deenergizes'and atarmature 165 opens the busy tone circuit; at armature 166 completes thetalking cirouit; at armature 167 prepares a point 1n the circuit. forrelay 110; and at armature 169 opens the circuit of relay 115 whichdeenergizes and causes relay 109 to deenergize. A short interval of timeafter its circuit is closed, relay 102 energizes and atarmature 122prepares the ringing circuit. At armature 126 relay 102 opens a point inthe holding circuit of relay 106 which is held up, however, over theback contacts of the A. C. relay 105; at armature 124 completes thecircuit for the A. C. relay 105; and at armatures 123 and 125 reversesthe flow of current over trunk conductors 9 and 10 so that the polarizedrelay 102 in the cord circuit CC operates to light the lamp L when theopera tor restores the dial key.

By the operation of the lamp L, the operator knows that the called lineis idle, and accordin l momentarily operates her ring- 111g key therebya plyin generator to trunk conductors 9an 10. C. relay 105 operatesresponsive thereto and opens the locking circuit of relay 106 whichaccordingly deenergizes. Relay 106, upon deenergizing, at armatures 131and 133 connects the generator to the called line. The rin 'n I circuitextends by way of generator GfiN? conductor 190, armature 122, up erwinding of relay 106, resting contact of armature 131 and said'armature,over the heavy talking conductors to the called subscribersline and thence back to ground at armature 133. Responsive to theoperation of this bell, the called subscriber will remove his receiver,thereby causing the operation of ring-cut-oif relay 106 over thepreviously traced ringing circuit. Relay 106, upon energizing, atarmature 132 again closes its locking circuit and-at armatures 131 and133 completes the talking circuit and also com letes a circuit forenergizing the battery feed relay 113 overthe called subscribers loop.Relay 113, upon energizing, at armature 163 completes an obvious circuitfor energizing relay 104. Relay 104, upon energizin at armatures-128 and129 disconnects all battery and ground connections from the trunkconductors 9 and 10 thereby providing a dry trunk in order to improvethe talking circuits and also at armature 128 closes a local holdingcircuit for the two windings of relay 127 in series. When the batteryand ground connections are cut off from the trunk conductors 9 and 10,polarized relay 2 in the cord circuit deenergizes and puts out the lamp,thereby signalling the operator that the called man has answered. Thetalking circuit may be traced over the heavy talking conductors in thewell known manner.

After conversation and responsive to the called subscriber replacing hisreceiver, relay 113 in the transmission selector repeater deenergizesand at armature 163-opens the circuit of relay 104. Relay 104, upondeenergizing, again connects battery and ground to the trunk conductors9 and 10 thereby operating the polarized relay 2 in the cord circuit tolight the lamp. L. The operator, upon perceiving the lighted conditionof the lamp L, will remove the plug P from the jack J, thereby openingthe circuit of line relay 107.

' Line relay 107, upon deenergizing, at armature 135 opens the circuitof release relay 108 which thereupon deenergizes. At armature 138,release relay 108 removes ground from release trunk conductor 121thereby causing the release of relay 117 and the release of theintermediate selector and connector as previously described. At armature141, slow to release relay 108 opens the locking circuit of ring-cut-offrelay 106 and at armature 139 closes a circuit for energizing therelease magnet 120. By the operation of the release magnet 120 thetransmission selector repeater is-returned to its normal position in thewell known manner.

Having described the operation which takes place in establishing a tollcall to an idle subscribers line, an explanation will now be given ofthe operation which takes place when the operator wishes to complete atoll connection to a subscribers line which is busy in an establishedlocal connection. It will now be assumed that substation A is the calledarty in anestablished local connection and that the toll operator wishesto establish a connection to such party.

The operation of the apparatus will be the same as described up to thetime that the connector shown in Fig. 5 comes to rest with its testWiper 465 in engagement with test contact 469 or multiples thereof.Since substattion A is busy in a local connection there will be a directground potential on test contact 469 and multiples thereof andaccordingly the busy relay 404 of the connector will be energized andlocked up as previously described. In this case, however, the circuit tothe upper winding of relays 402 and 403 are opened at armature 432 ofthe busy relay and ture 456 relay 408 connects the lower winding ofrelay 407 to conductor 343 as follows: ground through the lower windingof relay 407, armature 456, armature 427, armature 432, armature 452,and conductor 343.

Returning now to the toll transmission selector, relay 113 deenergizeswhen ground through the lower winding of relay 407 is connected toconductor 343 in place of the line-relay bridge. Relay 113 deenergizesslowly because its upper winding is shunted. The shunt circuit may betraced as follows: from grounded conductor 343, contact 338, wiper 335,conductor 332, conductor 197, contact 194, wiper 191, armature 182,armature 177 and its working contact, armature 134, and upper winding ofrelay 113 toground at armature 150. Relay 113, upon deenergizing, atarmature 163 opens the locking circuit of relay 116 which relaythereupondeenergizes. Relay 116, upon deenergizing, and at armature 175 completesa circuit for maintaining'relay 114 in operated position. This circuitextends from ground through the lower winding of relay 407, over thecircuit previously traced to armature 175 and thence by way of armature166, resistance 173 and Winding of relay 114 to battery. Relay 407 ofthe connector is not energized over this circuit on account of .thecombined resistances' of the winding of r'elay'114 and resistance 173. Acircuit may now be traced by way of the direct groundon'said contact469,01- multiples thereof, to conductor 341 from whence it extends byway of bank contact 340, Wipers 337, conductor 334, conductor 199,contact 196, wiper 193, armature 187,

- armature 181, armature 169 and its left hand in the cord circuit. Thebusy tone applied byway of conductor 148 indicates to the callingoperator that substation A is busy in'a local connection.

In case the operator desires to cut in on the established localconnection she will operate the key K thereby grounding conductors 9 and10in an obvious manner. He-

sponsive to groundin conductors 9 and 10,

the circuit of the lower winding of relay 113 and at armature 153prepares a point in the circuit for grounding conductor 199. At armature151, relay connects battery potential by way of the low resistancewinding of rotary magnet 119 to the winding of relay 114 and thence byway of resistance 173 to conductor 197. The connection of this batterypotential shunts relay 114 thereby causing said relay to deenergize andalso causes the switching relay 407 in the connector to energize overthe circuit previously traced through its lower winding. Two-step relay111, upon energizing in-its first step, operates only armatures 156 and157. At

. armature 156 relay 111 closes a circuit from ground at armature 141through both its windings in series to battery. "Relay 111, however,will not energize over this circuit because the lower winding is shuntedby ground at armature 149. At armature 157, relay 111 closes a shuntaround the contacts of armatures 167 thereby preparing a new circuit forholding relay 110 when slow actcircuit.

ing relay ll4deenergizes. When's'low-acting relay 114 finally fallsback, said rela at armatures 166 and 169 prepares the ta king Returningnow to the connector and whenrelay 407 energizes over the above-tracedcir-' cuit from-the transmission selector repeater, said relay-atarmatures 446 and 453 closes the talking circuit at armature 447disconnects conductor 341 from grounded contact 469; at armature 449connects ground through discriminating resistance 428 to test contact469; at armature 450 opens the. circuit to the busy relay 404 whichdeenergizes; at armature 451 completes a locking circuit for itself inseries with the 'vertical magnet; and at armature 452- disconnects thelower winding of relay 407 from conductor 343. At this time only relays401,

403, 405,, and 407 of the connector are in operated position. I

In the transmission selector repeater differential relay 103 deenergizeswhen the operator restores the ke K and said relay opens the circuit ofs ow acting relay 110.

Slow acting relay 110, upon deenergizing, removes ground from armature149, thereby permitting the two step rela 111 to fully operate to itssecond step. wo-step relay 111, upon energizing in its second step, atarmature 154 opens the circuit to the upper winding of relay 113; atarmature 155 prepares the circuit for opera-ting'the two step relay 112in its first step; .at armature 158 opens a point in the circuitextending to the lower winding of rela 113; andat armature 159 preparesa clrcuit for grounding conductor 199.

The operator may now converse with the desired subscriber and inform himof the desired toll connection. In case the operator desires to breakdown and release the local connection she may do so by again operatingtial relay 103 to operate. Relay 103, upon energizing, closes a circuitfor energizing relay 110 as follows 1 round by way of armature 163 andits resting contact, armature 143, armature 157, armature 127, andWinding of relay 110 to battery. At armature 153 relay 110 groundsconductor 199 and at armature 149 completes an obvious circuit forenergizing two-step relay 112 in its first step. Two-step relay 112does. not operate in its second step when it closesarmature 161 becauseof the shunt circuit around its lower winding. Two-step relay 112operates only armatures 160 and 161 in its first step and therefore acircuit may be traced from ground by way of armature 163 and its restingcontact, armature 143, armature 157, armature 145, armature 160, workingcontact of armature 131 and said armature, armatures 166, 175, and 182to conductor 197.

